1999mustang2000

ok my car is runnin rich and its gettin way worse...i have the air/fuel ratio gauge and its completely over in the rich side at times and then sumtimes a lil or none at all and idk wat to do...i have papers that say its been dyno tuned and blah but i also have a handheld tuner and it only adjusts wot fuel and its runnin rich on idle and it sputters a little and it has a slight hesitation and more power at times then at other times...ne help is needed and welcome and also how bad can this hurt my car thnx

contentsunderpressur

May be your o2 sensors going bad.

oxfordgt

More then likely you have a vacum leak.

1999mustang2000

Would a vacum leak or 02 sensors make it run rich though?

simmy8

yes they certainly can. the vaccum pulls air while your at idle, actually it pulls air in constantly but it does more work at idle, so if there isn't as much air being sucked in, it could run rich. If ur gage says that you are running rich at more than idle, i would def. say its a sensor. the O2 sensor measures the exhaust gasses and sends that info to the pcm to determine how much fuel to dump in. I would take it to a shop and let them have a look at it, they can determine what is going on.

1999mustang2000

if it was a vacumleeak wouldnt it die and not have ne power at all?

and it would be the rear o2 sensors right? or could it be the manifold ones 2?

oxfordgt

If you have a vacum leak it would cause the engine to shake and sputter at idle and would create a lean condition. The O2 sensors would see that and the computer will over correct causeing it to run rich as hell to keep the engine safe.

1999mustang2000

what if i turn off the rear o2's? with a tuner could that that help

oxfordgt

The rear O2s have nothing at all to do with how the engine runs.

blackstallion666

the only thing the rear o2's do is monitor the cats. And don't affect the running of the engine. Take a look over all your vacuum lines. Make the intake tube is tight etc. and take it from there.